B1122

Circuit Description
When you first turn the ignition switch to the RUN position, the Inflatable Restraint Sensing and Diagnostic Module (SDM) performs tests in order to diagnose the critical malfunctions within the module. The SDM measures the ignition positive voltage and the deployment loop voltages in order to ensure that they are within their respective normal voltage ranges. Then the SDM proceeds using the RESISTANCE MEASUREMENT test. During one portion of the RESISTANCE MEASUREMENT test, the SDM performs the following functions:
^ Grounds the DRIVER FRONTAL LOW terminal 9 through an internal current sink.
^ Connects the DRIVER FRONTAL HIGH terminal 10 to an internal constant current source. This current produces proportional voltage drops in the deployment loop.
^ Measures the voltage difference between the DRIVER FRONTAL HIGH and the DRIVER FRONTAL LOW.
^ Calculates the resistance of the driver frontal deployment loop using the measured voltage.

Conditions for Setting the DTC
^ The driver and passenger frontal deployment loops are not open.
^ The driver and passenger frontal deployment loops are not shorted to voltage.
^ The driver and passenger frontal deployment loops are not shorted to ground.
^ The driver frontal deployment loop resistance is less than 1.7 Ohms. The driver frontal deployment loop consists of the following components:
- The Inflatable Restraint Steering Wheel Module.
- The Inflatable Restraint Steering Wheel Module Coil.
- The harness wiring of circuit 347
- The harness wiring of circuit 348
- The connector terminal contact.

The RESISTANCE MEASUREMENT test checks for this malfunction. This test only occurs once each ignition cycle when Ignition Positive Voltage is within the normal operating voltage range.

Action Taken When the DTC Sets
^ The SDM sets a Diagnostic Trouble Code.
^ The SDM commands the instrument panel cluster (IPC) to turn ON the AIR BAG warning lamp.

Conditions for Clearing the MIL/DTC
^ Current DTC
The resistance of the driver frontal deployment loop is more than 1.7 Ohms and the ignition switch is cycled.
^ History DTC
- You issue a scan tool CLEAR CODES command.
- 250 malfunction free ignition cycles occur. When you issue a scan tool CLEAR CODES command and the malfunction is still present, the DTC will not reappear until the next ignition cycle.

Diagnostic Aids
The following conditions may cause an intermiffent condition:
^ A short circuit between circuit 347 and circuit 348.
^ A short circuit between circuit 347 and circuit 1403.
^ A short circuit between circuit 347 and circuit 1404.
^ A malfunctioning shorting bar on the Inflatable Restraint Steering Wheel Module connector.
^ A malfunctioning shorting bar on the Inflatable Restraint Steering Wheel Module Coil steering column connector.

When measurements are requested in this table, use J 39200 Digital Multimeter with the correct terminal adapter from J 35616-A Connector Test Adapter Kit. When a check for proper connection is requested, refer to Intermittents and Poor Connections. When a wire, connector or terminal repair is requested, use J 38125-B Terminal Repair Kit and refer to Wiring Repair. Intermittents and Poor Connections

Test Description
The numbers below refer to the step numbers on the diagnostic table:
2. This test checks for a short from circuit 1403 to circuit 347.
4. This test isolates the malfunction to one side of the Inflatable Restraint Steering Wheel Module Coil yellow 2-way connector.
5. This test determines whether the malfunction is due to the Inflatable Restraint Steering Wheel Module or the module coil.
9. This test checks for a short from circuit 347 to circuit 348.
11. This test checks for a short from circuit 347 to circuit 1404.